Did you know that you can change the color of hydrangea blooms? Martha tells us that it has to do with soil pH, or how acidic or alkaline the soil is. If the soil is acidic, the blossoms will be blue. In alkaline soil, the flowers will be pink. Walking through the garden the other day, she explained that to get blue hydrangeas, you should scratch one to two pounds of aluminum sulfate into the soil in November. To turn a blue hydrangea pink, scratch in two ounces of ground limestone per square yard. Who knew so much chemistry was involved!
Hey Francesca - here's a nice blue hydrangea mop-head. This shrub must be growing in acidic soil.